1. Field of the Invention
The present invention relates to a structure for a camshaft, which can be applied to an intake camshaft, an exhaust camshaft or the like for an internal combustion engine.
2. Description of the Related Art
In the intake camshaft or exhaust camshaft for the internal combustion engine, journals are enhanced in strength or rigidity against a bending load or a torsional torque which acts on a cam or a cam lobe and against a torsional torque which acts on a variable valve timing mechanism. One of the means for enhancing is disclosed in JP-A-9-228812.
In a related art disclosed in JP-A-9-228812, a camshaft is provided with a variable valve timing mechanism is supported in a cantilever manner by a cam journal on the outer side of the cam journal. A plurality of cam journals are tapered such that their external diameters take the maximum diameter on the side of the variable valve timing mechanism and become smaller as being away from the variable valve timing mechanism.